We are currently investigating the relation between genetic crossing over and the morphogenesis of the synaptonemal complex. Heat shocks, colchicine, cytochalasin, and inhibitors of DNA, RNA, and protein synthesis are used at concentrations determined to affect one of the above aspects of meiosis. By then carefully examining the remaining parameter at the time of and subsequent to treatment we are attempting to determine the manner in which they are interrelated. By using a combined genetic, cytogenetic, electron microscopic and molecular approach we bring many diverse techniques to bear on one system. In this way we are able for the first time to study intensively the major events of meiosis in one synchronous meiotic system.